The present invention relates to eyeglasses of the variable-lens type, and also to a positioning member particularly useful in such eyeglasses.
The invention is particularly useful with respect to bi-focal eyeglasses in which one part of the lenses has a higher power than the remainder. Usually, the two partial lenses are mounted in the frame with the stronger lens below the weaker one, so that the wearer normally sees through the weaker one, and lowers his eyes in order to see through the stronger one. Alternatively, the lower partial lens may be the weaker one in bi-focals for short-sighted (myopic) persons. Such an arrangement for looking through the lower partial lens is not entirely satisfactory for several reasons: First, it may be optically inefficient since the viewer may have to look through the bottom lens portion along the line oblique to the optial axis of that lens portion, rather than along the optical axis; secondly, it may be inconvenient to the wearer since he must frequently raise his head to an awkward position in order to look through the lower lens portion.